Computer based systems are becoming more mobile. This mobility often places an emphasis on usability. Usability is often extended by the ability to operate the equipment for longer periods of time. This time period is often related to the power consumption of the equipment, particularly in battery operated equipment. Thus, high power consumption may pose problems.
Numerous approaches to reducing power consumption have been tried. Powering off equipment when not in active use is one approach. Other approaches involve putting equipment in various lower power states, such as, idle mode, sleep mode, hibernation mode, etc. Such approaches may involve turning off portions of circuits or components, powering down subsystems and/or the main system, lowering supply voltages, altering clocking mechanisms, transferring data from, for example, random access memory (RAM) to disk storage, etc.
The powering up and down of subsystems without some form of communication between the subsystems or coordination may result in power cycling when not needed. This uncoordinated powering up and down may result in unneeded and unnecessary power consumption and present a problem for battery operated equipment.